Syphacia undetermined

Syphacia sp. (1)

Site of infection: Caecum and large intestine

Host species: Heteromys gaumeri

Localities: Hobonil ranch, Kuncheil cattle ranch (Yucatan) and Zoh Laguna community (Campeche)

Specimens deposited: CNHE 12026‒12028

GenBank accession numbers: OR271671, OR271672

Comments: The genus Syphacia is characterized by short and stout body; cephalic papillae near amphids; well defined esophagus bulb; and females with long tail, and elliptical eggs flattened at one side (Anderson et al. 2009). In the Americas, 20 species of Syphacia have been reported from native rodents (Robles 2010; Robles et al. 2014): Syphacia alata Quentin, Syphacia artica Tiner & Rausch, Syphacia carlitosi Robles & Navone, Syphacia criceti Quentin, Syphacia evaginata Hugot & Quentin, Syphacia hodarae Rojas Herrera, Miño, Notarnicola & Robles, Syphacia kinsellai Robles & Navone, Syphacia hugoti Robles, Panisse & Navone, Syphacia megadeiros, Quentin, Syphacia nigeriana Baylis, Syphacia obvelata (Rudolphi), Syphacia odilbaine Hugot & Quentin, Syphacia oryzomyos Quentin & Kinsella, Syphacia peromysci Harkema, Syphacia petrusewiczi rauschi Quentin, Syphacia phyllotios Quentin, Syphacia quentini Robles & Navone, Syphacia samorodini Erickson, Syphacia sigmodoni Quentin & Kinsella, and Syphacia venteli Travassos. Of these species, 18 were described in cricetids and 2 in murids. The specimens found in H. gaumeri had a cuticle with fine transverse striations, fields between transverse striations with shallow longitudinal depressions in females; a cephalic plate laterally-elongated in females (Figure 5F); cervical and lateral alae absents in both males and females; deirids well developed in females; male spicule 80‒110 long; female tail 580‒620; some females with slightly prominent vulva; and eggs 82‒90 long by 25‒30 wide (Figure 5G). Our specimens share a common feature (i.e., absence of cervical alae) with the following species: Sy. venteli, Sy. quentini, Sy. criceti, Sy. nigeriana, Sy. artica, Sy. megadeiros, Sy. oryzomyos, Sy. phyllotios, Sy. evaginata, Sy. odilbainea, Sy. kinsellai, and Sy. hugoti. However, the specimens from H. gaumeri differ from all the above species by having a longer (350‒480 in Sy. quentini and 500 in Sy. kinsellai) or shorter tail in females (750 in Sy. criceti, 850‒950 in Sy. nigeriana, 900‒1010 in Sy. artica, 740 in Sy. megadeiros, 630 in Sy. oryzomyos, 940 in Sy. phyllotios, 750 in Sy. evaginata, and 625‒975 in Sy. hugoti). In addition, Sy. venteli has a quadrangular cephalic plate and Sy. odilbaine has longer eggs (115), which allows us to differentiate them from our specimens. These differences suggest that our specimens may represent a species not described yet.

In Mexico, unidentified species of the genus Syphacia have been recorded in heteromyid species such as Perognathus flavus Baird in Chihuahua (Rendón-Franco et al. 2014), H. irroratus in Morelos (García-Prieto et al. 2012) and H. gaumeri in Yucatan (Panti-May et al. 2018). This is the first record of Syphacia in Campeche.